No sound effect?

I have the following code:
execute as @a[predicate=ctf:red1_capture] if data storage ctf:holders {red1:""} if score @s capture_timer_red1 matches 1200 run playsound minecraft:entity.ender_dragon.ambient master @a ~ ~ ~ 1 1
However, when I capture red flag 1, it doesn't make the dragon ambience sound.